Topical Oxidized Vitamin C (DHA) permeates through skin 12x faster than ascorbic acid.
Even though the human study below is from a company that produced the product with DHA, it seems to be very carefully done with practical considerations.
Topical Dehydroascorbic Acid (Oxidized Vitamin C) Permeates Stratum Corneum More Rapidly Than Ascorbic Acid
